As far as I can see, those references do not mention whether they have corrected for the fact that methane is a ~20x more potent greenhouse gas than CO2. Are they counting per volume or per potency? That is an incredibly important distinction. Which, to be honest, they should have made, one way or the other.
They are in the units "greenhouse gas emissions" which corrects for the extra potency. The sad thing is that people often double-correct for such things.
